In rotary drilling for the exploration for oil and gas, a liquid slurry know as drilling mud is utilized for maintenance and lubrication of the borehole created during the drilling operation. Typically the drilling mud system of a well includes a mud holding tank at the well surface located on or adjacent to the drilling rig and a network of pumps, mixers and mud supply lines. During rotary drilling operations, drilling mud is pumped from the mud holding tank, through the mud supply lines, down through the well bore at the desired rate and is returned to the surface of the well bore. The returned drilling mud carries with it drill cuttings from the bottom of the borehole produced as rotary drilling is advanced. When the circulating drilling mud, along with the carried drill cuttings, is returned to the surface, it is delivered to a screening device know as a “shaker” which serves as a sieve for removing the carried drill cuttings from the drilling mud. When the drill cuttings have been removed from the drilling mud by the shaker, the drilling mud is returned to the mud storage tank for reuse. The drill cuttings separated from the drilling mud are collected and conveyed to storage tanks for treating and disposal.
The storage and disposal of drill cuttings produced at a drilling location can present difficult problems. The drill cuttings removed from the borehole are typically comprised of shale, sand, hard clays, or shell and they are often coated with, or contain, residual contaminants from the drilling mud or from the borehole. The drill cuttings and their contaminants present environmental concerns that must be addressed during their disposal. The storage of the drill cuttings at the drill site prior to disposal can also present many problems, particularly on offshore drilling locations where storage space on drilling platforms is limited. The drill cuttings are typically stored on drilling locations in rigid cuttings boxes. These boxes are heavy, bulky and take up valuable platform deck space. Deck space must be allocated not only to cuttings boxes filled with cuttings that have been removed from the borehole but also to cuttings boxes waiting to be filled with drill cuttings that have been removed from the drilling mud.
Transporting the drill cuttings from a rig site to a disposal facility, whether from an onshore or an offshore drilling location, is also a concern because of the costs associated with transporting the bulky, heavy cuttings boxes to and from the well location. In addition, drill cuttings typically contain oil, petroleum distillates, and other environmentally unsuitable contaminates and often must undergo some treatment to remove or render inert any associated contaminates prior to their disposal. Such treatment is time consuming and expensive because it is typically conducted away from the rig location. Consequently, a need exists for improved methods of handling, processing, treating and disposing of drill cuttings produced at a drilling location.